This invention relates to vehicle windshields and wipers generally, and specifically to the type of blade lifting ramp found in patents classified in US class 15/250.19.
Vehicle windshield wipers engage the surface of the windshield with a fair degree of wiping pressure, which it is beneficial to relieve when the windshield wiper is stopped or "parked". This prevents the blade from taking a set over time. Typically, a park ramp is located near the park position of the wiper that hits and lifts the wiper arm, thereby pushing the blade up and off the glass to relieve the pressure on it.
Several interdependent considerations determine where such park ramps are located relative to the vehicle body and windshield. The park position of the wiper arm differs with vehicle designs, but is almost always near the lower edge of the windshield. In some cases, the wiper rests directly over the windshield surface, while in other designs the park position is below the lower windshield edge. Clearly, some part of the ramp must cross the path of the wiper as it moves to park in order to engage and lift it. Therefore, if the wiper rests directly over the windshield, the park ramp must extend over the windshield as well.
Wherever located, the ramp must be physically installed to some part of the vehicle body. The vehicle body has a flanged opening into which the windshield is installed, often with a peripheral bead of urethane adhesive. The installed position of the windshield's lower peripheral edge, both lateral and perpendicular, can vary, due to ordinary tolerances in the flanged opening and adhesive bead. The ramp may be installed directly to the body sheet metal, or to a trim piece surrounding the window, as is shown in older vehicle designs. More modern vehicle designs typically have a separate cowl panel with a flange that overlaps the lower edge of the windshield opening, and the park ramps are often affixed to it, or even made integral with it, rather than separable. The cowl panel is relatively long and narrow, and is often relatively thin, as well. Therefore, its installed position may also vary relative to the installed position of the upper surface of the windshield, as there is generally nothing to tie them directly together. Consequently, the position of the ramp relative to the wiper, which does follow the windshield surface rigorously, may also vary. In the potential worst case variation of lowest windshield surface and highest ramp, the lifting of the wiper at park may not occur as smoothly, and quietly as desired.
Another concern, in the case where the wiper and park ramp both overlay the windshield, is ease of windshield installation. It is desirable to lap the lower edge of the windshield over the cowl flange. This gives a shingling effect for shedding water, and leaves no gap between the two that would otherwise have to be covered. However, if the ramp extends over the windshield and is not separable, the windshield will have to be dropped in behind the ramps as it is installed. This is a more complex assembly motion than just moving the windshield straight down into the opening, and is more difficult to automate.